Bug fixes

● Support FaceID enabled devices
● Support File App
● Minor bug fixes

● bug fixes for Dropbox & GoogleDrive

● bug fixes on iOS 10.3.x

● Add option for iTunes backup and iCloud backup.
● minor bug fix.

● download books in background.
● minor bug fix.

● page orientation bug fix.
● minor bug fix.

● PDF file link bug (caused by Exported UTIs) is fixed.

● Support iPhone6/6s and plus.
● 3D touch shortcuts.